FIG. 1 shows a typical configuration of a large area network, such as the Internet. Multiple geographically dispersed user client systems 100 are connected through user Internet Service Providers (ISPs) 102 to the network “cloud” 104 comprising the Internet backbone communication transport systems. Requests for information or services by a client application program executing on a user client system 100 may be routed through multiple server ISPs 106 through a router 108 to a web server 110. The web server 110 retrieves or generates the requested information or provides the requested service, and communicates a response to the requesting client application.
Various attempts have been made to actively assess the performance (e.g., response time, transmission problems, etc.) of Internet connections. Some current methods use active measurement of various network or server components that are dedicated to performance measurement. For example, conventional Internet Control Message Protocol (ICMP) “ping” and “traceroute” commands can be used to measure the performance of the network connections between a client terminal and a server. However, these commands are frequently transmitted with a different (often lower) priority than the protocols used by applications run by users for “web surfing”. Accordingly, inaccurate (i.e., false positive) measurements are common.
Attempts have been made to actively measure Internet connections using the same protocols used by end-user applications, such as the HyperText Transfer Protocol (HTTP) “GET” command. These approaches typically use computer programs (sometimes known as “hosts”, “agents”, or “beacons”) residing on measurement instrumentation capable of communicating with Internet protocols. However, such computer programs are limited to assessing network paths only from the specific network nodes on which they are executing. Further these techniques inject traffic into sometimes overburdened Internet, WAN, or LAN infrastructures, causing the measurement process to change the characteristics being measured. Additionally, these techniques are relatively expensive to implement.
A further problem of all of these active or injected measurement approaches is that they generate non-value added communication traffic for both local and large area network infrastructures.